Isolation and Biological Characterization of an Escherichia coli Phage

WANG Xue; YANG Zhenhong; WANG Shihui; LIN Bokun

doi:10.15933/j.cnki.1004-3268.2026.01.014

Abstract：To explore the biological characteristics of Escherichia coli phage and evaluate its antibacterial application potential,a strain of Escherichia coli phage was isolated from the lake water samples of Guangdong Medical University,named PE62.Biological characteristics of PE62 were systematically analyzed using methods including spot assay,double-layer agar plate method,transmission electron microscopy observation,whole-genome sequencing,one-step growth curve assay,and time-kill assay,and its biofilm eradication ability was evaluated via crystal violet staining.The results showed that PE62 could form transparent plaques with a diameter of approximately 1-1.5 mm on the lawn of enteroaggregative Escherichia coli(EAEC)strain E533.Transmission electron microscopy observation revealed that it possessed a head and a tail structure,belonging to the Myoviridae family.The lysis spectrum test showed that PE62 could lyse a variety of pathogenic Escherichia coli(including intestinal agglomeration,intestinal pathogenicity and enterotoxicity),Salmonella and Shigella.The phage maintained activity within the range of 25-55℃and pH 2-11,exhibiting good temperature and acid-base stability.Its optimal multiplicity of infection(MOI)was 0.1.The one-step growth curve showed that the latent period was approximately 40 min,the burst period was also 40 min,and the burst size was about 585.Whole-genome analysis revealed that PE62 had a double-stranded circular DNA with a G+C content of 35.52%and did not carry known virulence factors or antibiotic resistance genes.In vitro bactericidal assays showed that PE62 exhibited excellent bactericidal activity against host bacteria and achieved a biofilm clearance rate of 27.9%.In conclusion,PE62 possesses a broad host range,good environmental adaptability,and strong in vitro bactericidal as well as biofilm eradication capabilities,indicating promising potential for application in the prevention and control of Escherichia coli infections.